One quick note.  Under current accounting standards, as I understand
them, there's one peculiarity worth considering.  If the promise to give
is considered an enforcable obligation, then the revenue is booked for
the period in which the promise was given, not the period in which the
funds were actually received.  I really don't know the particulars for
end-of-year gifts, but this is one complexity to add to them.

Alex Barker
Chief Curator & Interim Director
Dallas Museum of Natural History